Saturable reactor voltage regulator with series connected main and control inductance windings



June 8, 1965 P. ESSINGER 3,188,555

SATURABLE REACTOR VOLTAGE REGULATOR WITH SERIES CONNECTED MAIN ANDCONTROL INDUCTANCE WINDINGS Filed D90. 27,. 1960 FIG. 1

35 l 40 :LUD 25 50 55 3a 2 52 54 21 56 59 FIG. 3 FIG. 4

FIG 5 I/VVENTOR PIERRE ESSINGER (BY/4 W AUTO/FIVE) United States Patent3,188,555 SATURABLE REACTOR VOLTAGE REGULATOR WITH SERIES CONNECTED MAINAND CON- TROL INDUCTAN CE WINDINGS PierreEssinger, Yorktown Heights,N.Y., assignor to International Business Machines Corporation, New York,N.Y., a corporation of New York f Filed Dec. 27, 1960, Ser. No. 78,577

Claims. (Cl. 323-89) This invention relates generally to inductancedevices and it has reference in particular to a saturationcontrolledchoke.

One object of this invention is to provide an inductance device havingimproved operating characteristics.

Another object of this invention is to provide for using a controlledinductance choke having a main winding and an auxiliary saturationcontrol winding to make the operating characteristics more linear.

Yet another object of this invention is to provide a con trollableinductance device having a magnetic core with a main winding thereon andan opening therein with a saturation control winding arranged in afigure-8 configuration therethrough.

It is also an object of the present inventiomto provide for using asaturation-controlled choke device as a controllable phase shift device.

Another important object of this invention is to provide for using asaturation-controlled choke device as a frequency modulator in aresonant tank circuit.

It is also an important object of this invention to providea linearswinging choke having a main impedance winding and a serially connectedsaturation control winding disposed to be connected in either analternating cur- -rent circuit or in an ulfiitered rectified alternatingcurrent circuit.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention as illustrated inthe accompanying drawings.

In the drawings:

FIG. 1 is a schematic diagram showing a saturationcontrolled chokeembodying the invention in one of its forms.

FIG. 2 illustrates curves showing the relative operating characteristicsof the choke of FIG. 1 and a typical swinging choke.

FIG. 3 is a schematic diagram of a phase shift circuit embodying theinvention. I

FIG. 4 is a schematic diagram of a phase shift circuit also embodyingthe invention.

FIG. 5 is a schematic diagram showing an application of the invention asa modulator in a PM resonant tank circuit.

, In practicing the invention in one of its forms, a threelegged core ofthe magnetic material has air gaps in each of the legs and a window inthe central leg. A main inductance winding on the central leg isconnected in a series with an unfiltered rectified alternating currentsource and a load. A figure-8 saturation control winding is located onthe central leg, passing around portions of the leg and through thewindow, and being connected in series with the main inductance windingso as to control saturation of the central leg and provide a more linearswinging choke characteristic.

Referring particularly to FIG. 1 of the drawing, the

reference numeral 10 may denote generally a saturationcontrolledinductance or choke device which is connected in circuit between a loaddevice such as the resistor 12 and a source of pulsating current such asan unfiltered rectified alternating current source 14. A filter capaci-3,188,555 Patented June 8, 1965 tor 13 is connected across the load 12when rectified A.-C. is used.

The choke device 10 comprises in the present instance a three-leggedcore of magnetic material having outer legs 15 and a central leg 16connected by end portions 18. The legs 15 and 16 are each provided withan air gap 20, while the central leg 16 is further provided with anopening or window 22. A main inductance winding 25 is disposed on thecentral leg 16 and is connected in series circuit'relation with thesource 14 and the load 12.

In order to maintain a critical inductance condition and provide a morelinear operating characteristic for the choke device 10, which may bedisposed to operate as a swinging choke under varying load conditions,an auxiliary saturation-control winding 27 is also disposed aboutportions of the central leg portion 16, passing through the window 22 soas to provide a figure-8 configuration which results in a localizedcontrol flux about the window. While the control winding 27 may beconnected to a separate source of direct current, in-phase alternatingcurrent or pulsating direct current, depending on the particularapplication, in the present instance, the winding 27 is connected inseries with the main inductance winding 25 to the output of theunfiltered rectified A.-C. source 14 so as to provide a local fluxaround the window 22 in accordance with the load current for controllingthe inductance effects of the load current.

Referring to FIG. 2, it will be seen from the curve a that theinductance device 10 has a substantially linear operating characteristicfrom no load to a full load condition of approximately 12.5 amperes,after which saturation causes the characteristic to droop considerably.This substantially linear curve up to full load conditions is a greatimprovement over the characteristic curve b which was taken for atypical type of swinging choke of approximately the same rating, but notembodying the features of the present invention. It will be noted thatthe curve b has a substantially drooping characteristic throughout itsoperating range and is not nearly as linear as the curve a for the chokedevice of the present invention.

A saturation-controlled choke device 10 such as shown in FIG. 1 may bereadily utilized as a variable inductance device for controlling thephase relations of voltages in a phase shift circuit such as shown inFIG. 3. By connecting the inductance winding 25 in series with analternating cur-rent source 30 and a capacitor 32, and connecting thecontrol winding 27 to a variable direct current source, the relativevalues of the inductive and capacitative voltages between the terminals33 and 35 may be made to vary with different degrees of saturation ofthe choke device it). For example, as the current through the controlwinding 27 is increased, the inductance of the Winding 25 decreases andthe voltage between the terminals 34 and 35 will decrease, while thevoltage between the terminals 33 and 34 will increase. Since the phaserelations of the voltages across the inductance Winding 25 and thecapacitor 32 are substantially opposite, this provides a readilycontrollable phase shift circuit.

Referring to FIG. 4, it will be seen that a somewhat similar phase shiftcircuit employing a saturation-controlled choke device 10 is provided byutilizing a resistor 36 in place of the capacitor 32. By varying thecontrol current through the saturation control winding 27, the voltageacross the inductance winding 25 is varied, and the phase relations ofthe voltages between the terminals 38-899 and 3840 may be readilyvaried.

Referring to FIG. 5, it will be seen that a saturationcontrolled chokedevice 50 similar to that shown in FIG. 1 may be utilized as a variableinductance device in a resonant tank circuit 52 for modulating thefrequency of device 5d may be provided with a center tap 57, but inother respects, it is substantially identical with thesaturation-controlled choke device it hereinbefore described.

A capacitor 53 is connected across the impedance wind-' ing 56 toprovide a tuned circuit, andthe tank circuit is connected to theoscillator 55, having the centertap 57 connected to the cathode 6%) ofthe oscillator, with a connection at 62 intermediate the capacitor andimpedance winding 56 being connected to the grid 64 of the oscillator,while a connection 65 from the lower end of the tank circuit isconnected to ground. By varying the con-1 while the outer legs areapproximately inch wide.

The window in the central leg is approximately /2 inch wide by inchhigh, and the air gaps in the outer legs are about .020 inch. The maininductance winding comprises 75 turns and the control winding 5 turns oneach side, of the window connectedin a figure-8 configuration. The curvea of FIG. 2 was made using this embodiment with a 60 cycle load up toapproximately 12 /2 amperes.

From the above description and the accompanying e an oscillator 55. Theinductance winding 56 of the choke drawing, it will be apparent that thepresent invention provides a simple and effective manner for controllingthe inductance of a choke. V The figure-8 control winding provides aneffective flux control of the core without introducing the usualcirculating D.-C. flux, since the control flux in the present instanceis localized about the window. This method of control may be appliedin aplurality of manners for either providing more linear characteristicsfor the choke or for varying the inductance for control purposes.three-legged core structure, however, as a simple core structure withair gaps and a figure-8 saturation control winding may be readily used.

.While the invention has been particularly shown and described with-reference to a preferred embodiment there; of, it will be understoodby those skilled in the art that other changes in form and details maybe made therein without departing from the spirit and scope of theinvention. i

What is claimed is: I g 1. In an inductance device, a core of magneticmaterial having an opening through a portion thereof and an air gaptherein, an inductance winding on said ,core and 'a saturation controlwinding connected in series with the inductance winding, said controlwinding passing through said opening with a figure-8 configuration so asto provide a local control flux about the opening in accordance with thecurrent in the inductance winding.

2. Inalinear swinging choke, athree-legged'core of magnetic materialhaving an opening through the central leg and an air gap in each of thelegs, an inductance winding wound about the central leg, and a controlwinding connected in series with the inductance winding, said controlwinding being wound about the central leg through said opening in afigure-8 configuration.

. 3. In combination with a circuit connected to an unfiltered rectifiedalternating current source, a linear choke having a three-legged core ofmagnetic material'with an opening in the central leg and an air gap ineach of the 1 legs, an inductance winding on the central leg connectedin circuit with said circuit, and an auxiliary control winding connectedin series with the inductance winding,

said control winding being wound through saidopening in a figure-8configuration.

4. In an inductance device, a core of magnetic material having an airgap therein and an opening through a portion of said core, an inductancewinding on said core for connection in series with a source ofperiodically varying current, and a load and a control winding passingthrough said opening having a figure-8 configuration and connected tovary the self inductance of the inductance Winding.

5. A reactor comprising, a three-legged core of magv netic materialhaving a central leg with an opening there- The invention is not limitedto a through and each leg having an air gap therein, an inductancewinding disposed about said central leg, and a control winding on saidcentral leg passing through said opening and having a figure-8configuration, said control winding being connected in circuit with saidinductance Winding for controlling the self inductance thereof.

7 References Cited by the'Examiner UNITED STATES PATENTS 2,664,541 12/53Henderson 336.

2,864,993 12/58 Schober 32389 2,904,743 9/59 McClain 323-89 2,953,7399/60 Duinker 323-89 3,148,326 9/64 Baycura et a1 32389 LLOYD MCCOLLUM,Primary Examiner. MILTON O. HIRSHFIELD, Examiner.

Adams. 336-226

1. IN AN INDUCTANCE DEVICE, A CORE OF MAGNETIC MATERIAL HAVING ANOPENING THROUGH A PORTION THEREOF AND AN AIR GAP THEREIN, AN INDUCTANCEWINDING ON SAID CORE AND A SATURATION CONTROL WINDING CONNECTED INSERIES WITH THE INDUCTANCE WINDING, SAID CONTROL WINDING PASSING THROUGHSAID OPENING WITH A FIGURE-8 CONFIGURATION SO AS TO PROVIDE A LOCALCONTROL FLUX ABOUT THE OPENING IN ACCORDANCE WITH THE CURRENT IN THEINDUCTANCE WINDING.